This is a large change from v3.x.
- Switched from through hole atmega328 to surface mount atmega328.
- Added ISP header for programming new SMD 328 bootloader.
- Added on-board FTDI adapter so uploading code is as easy as plugging in a mini USB cable.
-- Still has 6 pin FTDI header so you can still use external FTDI adapter to program.
-- Added status LEDs for on-board FTDI uploading (rx/tx).
- Switched to a new voltage regulator that MUCH more common/easy to find.
-- Added heatsink area for vreg.
- Changed the way the board is powered; now all power inputs go through their own diode, and THEN to the vreg, so they're all isolated, and now the vreg output is a clean 3.3v.
OSHPark v4.1 PCB